Carrier systems, including a guide track and a carrier member movable along a guide track are particularly useful for moving product over an extended distance. Furthermore, the use of recirculating balls in a carrier system is very effective for load bearing purposes.
There are a number of prior art arrangements including a carrier movable through recirculating balls along a guide. By way of example, U.S. Pat. No. 4,648,726 shows a carrier movable along a guide member using recirculating balls. However, the raceway for the balls extends in a horizontal direction so that the balls themselves not only bear the load but additionally provides the sole means of support between the carrier member and the guide.
U.S. Pat. No. 4,527,840 issued July 9, 1985 to Mugglestone also describes a carrier system where the balls recirculate in a horizontal fashion. Furthermore, in the Mugglestone arrangement the balls are totally enclosed within the carrier member which therefore includes a complicated structure to ride along the guide rail.
U.S. Pat. Nos. 4,420,193 dated Dec. 13, 1983, 4,549,770 dated Oct. 29, 1985 and 4,692,039 dated Sept. 8, 1987 and all issued to Teramachi describe different forms of carrier systems including a guide rail and carrier member or bearing which moves along the guide rail. Once again, each of these structures is relatively complicated and specifically requires the use of a double set of recirculating balls at each side of the set up. In addition none of the balls in each set recirculate in a vertical fashion again placing them in an awkward load bearing position. Furthermore, the carrier member itself in each of these patented structures is provided with a relatively inaccessible completely closed channel for recirculation of the balls.